GLHX - thanks, I appreciate your reply and input.

Re Sensor 3 - my bad - that was a typo. I meant to say Long Term Fuel Trim Bank 3. I pulled whatever PIDs I saw with fuel trim in the name. These PIDS are shown in the graphs attached to my previous post. I did not see a bank 2 sensor (i'm using DashCommand for Ipad). Should I be looking at the oxygen sensor fuel trims (e.g. SAE.O2S11.SHRTFT)? Because I don't see a long term fuel trim from this sensor. The only long term I see is SAE.LONGFT1 and SAE.LONGFT3.

O2 voltages at idle are always in the 0.1-0.8 range. I'll try cleaning the MAP sensor (the R53 has a TMAP and MAP but not a MAF) with CRC MAF sensor cleaner. Will then move on to checking thermostat and for vacuum leaks (I imagine I'll have to take it to the shop for that).

Thanks again for the detailed info - it's really useful

 

It's hard to tell from your graphs. I did structured testing with 3 graphs.
Idle
Off idle
Long flat run.

My idle was fine. Long flat run wasn't bad.
Off idle was slightly off.

I then compared my graphs to the same graphs of a perfect car. We found maf sensor to be 15% different. I replaced it and everything is normal.

LTFT are an average of short term trims. Remember that......:thumbsup

You look at the LTFT once....see them being high.
You then look at the short term trims to see where the high numbers are coming from... This is where the problems are. They are in high numbers of the STFT. If they are high at idle....problem is at idle. If you run flat open road consistently..and see them spike up and down. Then the problem is there. Mine shot up when I stepped on the gas. I compared it to someone else who ran the same test.

He ran flat open. Page hit idle.....mine and his were the same.

But off idle they were different slightly.....just enough to soft fail and not know for sure. I replaced it on faith that the maf was bad with these small 15% differences. I cleaned my maf......didn't work. The guy who put it in there bought the maf from china. A big no no with European cars. They are expensive because platinum isn't cheap.

 

Also......load test

To check fuel pressure and fuel trims.

Step on the brake....rev the engine in gear just enough to load the engine. Your fuel pressure shouldn't change. You need to think like this....."I'm running lean"
Why......not enough gas,.,,,,,,too much air......or computer reading either one wrong. No enough gas could be weak fuel pump or filter,,,,,bad regulator. Load testing solves this. Go to auto parts store. Rent large gauge kit. It has special adapter for your rail. . Then load test

 

Thanks - I appreciate it. I'll do some more testing over the next few days. I'm just glad I seem to be honing in on my rough idle and low mileage issues. Will post more results here when I have 'em...